FAIR VALUE MEASUREMENTS: (Details) - Fair value measured on a recurring basis - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 28, 2014
Estimated Fair Value
Fair value measurements
Cash and cash equivalents	$ 87,005	$ 100,108	$ 57,091
Available for sale securities	133,491	131,347	132,688
Trading securities	75,830	71,682	68,582
Total assets measured at fair value	292,810	300,461	258,592
Estimated Fair Value \| Foreign currency forward contracts
Fair value measurements
Derivative instruments, net	(2,494)	(1,939)	81
Estimated Fair Value \| Commodity futures contracts
Fair value measurements
Derivative instruments, net	(1,022)	(737)	150
Level 1
Fair value measurements
Cash and cash equivalents	87,005	100,108	57,091
Available for sale securities	2,454	2,446
Trading securities	75,830	71,682	68,582
Total assets measured at fair value	164,267	173,499	125,823
Level 1 \| Commodity futures contracts
Fair value measurements
Derivative instruments, net	(1,022)	(737)	150
Level 2
Fair value measurements
Available for sale securities	131,037	128,901	132,688
Total assets measured at fair value	128,543	126,962	132,769
Level 2 \| Foreign currency forward contracts
Fair value measurements
Derivative instruments, net	$ (2,494)	$ (1,939)	$ 81

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value of the assets less the liabilities of a derivative or group of derivatives.

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Fair value of asset after deduction of liability.

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Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

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